Rated 2 out of 5 stars
No 'Make Scriptlet' menu item for bookmarklets /already in your Bookmarks/. I await further updates.
Being able to create a new scriptlet from the Add-ons Mgr. would be a basic feature--perhaps using Scratchpad (and some already existing bits of code a user might have for execution because certain commands were restricted from bookmarklets [will this add-on remedy that?]).
Rated 1 out of 5 stars
Poor description and no "settings" button in about:addons page, so I don't even know how to use this add-on.
Edit: found the proper description: http://work.erikvold.com/addons/2013/06/10/on-scriptlets.html
It doesn't work with some bookmarklets (e.g. http://www.bookmarklets.com/tools/convert/index.phtml ), it loses all the installed ones from their positions (puts them back to "customize panels view") if you disable and re-enable this add-on.
It doesn't create a sub-group "bookmarklets" in add-ons manager to manage installed bookmarklets.